GLORIA

GEOMAR Library Ocean Research Information Access

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Material
Language
  • 1
    In: Medical Physics, Wiley, Vol. 49, No. 7 ( 2022-07), p. 4430-4444
    Abstract: Quantitative in vivo molecular imaging of fine brain structures requires high‐spatial resolution and high‐sensitivity. Positron emission tomography (PET) is an attractive candidate to introduce molecular imaging into standard clinical care due to its highly targeted and versatile imaging capabilities based on the radiotracer being used. However, PET suffers from relatively poor spatial resolution compared to other clinical imaging modalities, which limits its ability to accurately quantify radiotracer uptake in brain regions and nuclei smaller than 3 mm in diameter. Here we introduce a new practical and cost‐effective high‐resolution and high‐sensitivity brain‐dedicated PET scanner, using our depth‐encoding Prism‐PET detector modules arranged in a conformal decagon geometry, to substantially reduce the partial volume effect and enable accurate radiotracer uptake quantification in small subcortical nuclei. Methods Two Prism‐PET brain scanner setups were proposed based on our 4‐to‐1 and 9‐to‐1 coupling of scintillators to readout pixels using  mm 3 and  mm 3 crystal columns, respectively. Monte Carlo simulations of our Prism‐PET scanners, Siemens Biograph Vision, and United Imaging EXPLORER were performed using Geant4 application for tomographic emission (GATE). National Electrical Manufacturers Association (NEMA) standard was followed for the evaluation of spatial resolution, sensitivity, and count‐rate performance. An ultra‐micro hot spot phantom was simulated for assessing image quality. A modified Zubal brain phantom was utilized for radiotracer imaging simulations of 5‐HT 1A receptors, which are abundant in the raphe nuclei (RN), and norepinephrine transporters, which are highly concentrated in the bilateral locus coeruleus (LC). Results The Prism‐PET brain scanner with 1.5 mm crystals is superior to that with 1 mm crystals as the former offers better depth‐of‐interaction (DOI) resolution, which is key to realizing compact and conformal PET scanner geometries. We achieved uniform 1.3 mm full‐width‐at‐half‐maximum (FWHM) spatial resolutions across the entire transaxial field‐of‐view (FOV), a NEMA sensitivity of 52.1 kcps/MBq, and a peak noise equivalent count rate (NECR) of 957.8 kcps at 25.2 kBq/mL using 450–650 keV energy window. Hot spot phantom results demonstrate that our scanner can resolve regions as small as 1.35 mm in diameter at both center and 10 cm away from the center of the transaixal FOV. Both 5‐HT 1A receptor and norepinephrine transporter brain simulations prove that our Prism‐PET scanner enables accurate quantification of radiotracer uptake in small brain regions, with a 1.8‐fold and 2.6‐fold improvement in the dorsal RN as well as a 3.2‐fold and 4.4‐fold improvement in the bilateral LC compared to the Biograph Vision and EXPLORER, respectively. Conclusions Based on our simulation results, the proposed high‐resolution and high‐sensitivity Prism‐PET brain scanner is a promising cost‐effective candidate to achieve quantitative molecular neuroimaging of small but important brain regions with PET clinically viable.
    Type of Medium: Online Resource
    ISSN: 0094-2405 , 2473-4209
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 1466421-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    In: Medical Physics, Wiley, Vol. 48, No. 3 ( 2021-03), p. 1019-1025
    Abstract: Depth of interaction (DOI) readout in PET imaging has been researched in efforts to mitigate parallax error, which would enable the development of small diameter, high‐resolution PET scanners. However, DOI PET has not yet been commercialized due to the lack of practical, cost‐effective, and data efficient DOI readout methods. The rationale for this study was to develop a supervised machine learning algorithm for DOI estimation in PET that can be trained and deployed on unique sets of crystals. Methods Depth collimated flood data was experimentally acquired using a Na‐22 source with a depth‐encoding single‐ended readout Prism‐PET module consisting of lutetium yttrium orthosilicate (LYSO) crystals coupled 4‐to‐1 to 3×3  silicon photomultiplier (SiPM) pixels on one end and a segmented prismatoid light guide array on the other end. A convolutional neural network (CNN) was trained to perform DOI estimation on data from center, edge and corner crystals in the Prism‐PET module using (a) all non‐zero readout pixels and (b) only the 4 highest readout signals per event. CNN testing was performed on data from crystals not included in CNN training. Results An average DOI resolution of 1.84 mm full width at half maximum (FWHM) across all crystals was achieved when using all readout signals per event with the CNN compared to 3.04 mm FWHM DOI resolution using classical estimation. When using only the 4 highest signals per event, an average DOI resolution of 1.92 mm FWHM was achieved, representing only a 4% dropoff in CNN performance compared to using all non‐zero pixels per event. Conclusions Our CNN‐based DOI estimation algorithm provides the best reported DOI resolution in a single‐ended readout module and can be readily deployed on crystals not used for model training.
    Type of Medium: Online Resource
    ISSN: 0094-2405 , 2473-4209
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 1466421-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Online Resource
    Online Resource
    Institute of Electrical and Electronics Engineers (IEEE) ; 2022
    In:  IEEE Transactions on Radiation and Plasma Medical Sciences Vol. 6, No. 5 ( 2022-5), p. 529-536
    In: IEEE Transactions on Radiation and Plasma Medical Sciences, Institute of Electrical and Electronics Engineers (IEEE), Vol. 6, No. 5 ( 2022-5), p. 529-536
    Type of Medium: Online Resource
    ISSN: 2469-7311 , 2469-7303
    Language: Unknown
    Publisher: Institute of Electrical and Electronics Engineers (IEEE)
    Publication Date: 2022
    detail.hit.zdb_id: 2867672-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    In: Medical Physics, Wiley, Vol. 50, No. 7 ( 2023-07), p. 4234-4243
    Abstract: Given the large number of readout pixels in clinical positron emission tomography (PET) scanners, signal multiplexing is an indispensable feature to reduce scanner complexity, power consumption, heat output, and cost. Purpose In this paper, we introduce interleaved multiplexing (iMux) scheme that utilizes the characteristic light‐sharing pattern of depth‐encoding Prism‐PET detector modules with single‐ended readout. Methods In the iMux readout, four anodes from every other silicon photomultiplier (SiPM) pixels across rows and columns, which overlap with four distinct light guides, are connected to the same application‐specific integrated circuit (ASIC) channel. The 4‐to‐1 coupled Prism‐PET detector module was used which consisted of a 16 ×  16 array of 1.5 × 1.5 × 20 mm 3 lutetium yttrium oxyorthosilicate (LYSO) scintillator crystals coupled to an 8 × 8 array with 3 ×  3 mm 2 SiPM pixels. A deep learning‐based demultiplexing model was investigated to recover the encoded energy signals. Two different experiments were performed with non‐multiplexed and multiplexed readouts to evaluate the spatial, depth of interaction (DOI), and timing resolutions of our proposed iMux scheme. Results The measured flood histograms, using the decoded energy signals from our deep learning‐based demultiplexing architecture, achieved perfect crystal identification of events with negligible decoding error. The average energy, DOI, and timing resolutions were 9.6 ± 1.5%, 2.9 ± 0.9 mm, and 266 ± 19 ps for non‐multiplexed readout and 10.3 ± 1.6%, 2.8 ± 0.8 mm, and 311 ± 28 ps for multiplexed readout, respectively. Conclusions Our proposed iMux scheme improves on the already cost‐effective and high‐resolution Prism‐PET detector module and provides 16‐to‐1 crystal‐to‐readout multiplexing without appreciable performance degradation. Also, only four SiPM pixels are shorted together in the 8 ×  8 array to achieve 4‐to‐1 pixel‐to‐readout multiplexing, resulting in lower capacitance per multiplexed channel.
    Type of Medium: Online Resource
    ISSN: 0094-2405 , 2473-4209
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 1466421-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    In: Medical Physics, Wiley, Vol. 50, No. 6 ( 2023-06), p. 3401-3417
    Abstract: Positron emission tomography (PET) has had a transformative impact on oncological and neurological applications. However, still much of PET's potential remains untapped with limitations primarily driven by low spatial resolution, which severely hampers accurate quantitative PET imaging via the partial volume effect (PVE). Purpose We present experimental results of a practical and cost‐effective ultra‐high resolution brain‐dedicated PET scanner, using our depth‐encoding Prism‐PET detectors arranged along a compact and conformal gantry, showing substantial reduction in PVE and accurate radiotracer uptake quantification in small regions. Methods The decagon‐shaped prototype scanner has a long diameter of 38.5 cm, a short diameter of 29.1 cm, and an axial field‐of‐view (FOV) of 25.5 mm with a single ring of 40 Prism‐PET detector modules. Each module comprises a 16 × 16 array of 1.5 × 1.5 × 20‐mm 3 lutetium yttrium oxyorthosillicate (LYSO) scintillator crystals coupled 4‐to‐1 to an 8 × 8 array of silicon photomultiplier (SiPM) pixels on one end and to a prismatoid light guide array on the opposite end. The scanner's performance was evaluated by measuring depth‐of‐interaction (DOI) resolution, energy resolution, timing resolution, spatial resolution, sensitivity, and image quality of ultra‐micro Derenzo and three‐dimensional (3D) Hoffman brain phantoms. Results The full width at half maximum (FWHM) DOI, energy, and timing resolutions of the scanner are 2.85 mm, 12.6%, and 271 ps, respectively. Not considering artifacts due to mechanical misalignment of detector blocks, the intrinsic spatial resolution is 0.89‐mm FWHM. Point source images reconstructed with 3D filtered back‐projection (FBP) show an average spatial resolution of 1.53‐mm FWHM across the entire FOV. The peak absolute sensitivity is 1.2% for an energy window of 400−650 keV. The ultra‐micro Derenzo phantom study demonstrates the highest reported spatial resolution performance for a human brain PET scanner with perfect reconstruction of 1.00‐mm diameter hot‐rods. Reconstructed images of customized Hoffman brain phantoms prove that Prism‐PET enables accurate radiotracer uptake quantification in small brain regions (2–3 mm). Conclusions Prism‐PET will substantially strengthen the utility of quantitative PET in neurology for early diagnosis of neurodegenerative diseases, and in neuro‐oncology for improved management of both primary and metastatic brain tumors.
    Type of Medium: Online Resource
    ISSN: 0094-2405 , 2473-4209
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 1466421-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    In: International Journal of Cancer, Wiley, Vol. 133, No. 8 ( 2013-10-15), p. 1982-1993
    Type of Medium: Online Resource
    ISSN: 0020-7136
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 218257-9
    detail.hit.zdb_id: 1474822-8
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    In: Environmental Health, Springer Science and Business Media LLC, Vol. 21, No. 1 ( 2022-01-04)
    Abstract: The incidence rates of thyroid tumors and nodular goiter show an upward trend worldwide. There are limited reports on the risk of perchlorate and iodine on thyroid tumors, but evidence from population studies is scarce, and their impact on thyroid function is still uncertain. Therefore, the objective of this study was to investigate the association of perchlorate and iodine with the risk of nodular goiter (NG), papillary thyroid microcarcinoma (PTMC), and papillary thyroid carcinoma (PTC) and to assess the correlation between perchlorate and iodine with thyroid function indicators. Methods A case–control population consisting of 184 pairs of thyroid tumors and nodular goiter matched by gender and age (±2 years) was recruited in this study. Serum and urine samples were collected from each participant. Thyroid function indicators in serum were tested by automatic chemical immunofluorescence, and perchlorate and iodine levels in urine were determined by ultra-high performance liquid chromatography tandem-mass spectrometry and inductively coupled plasma-mass spectrometry, respectively. Conditional logistic regressions and multiple linear regressions were used to analyze the associations. Results Urinary perchlorate concentration was significantly higher in total cases, NG and PTC than in the corresponding controls ( P   〈  0.05). Perchlorate was positively associated with PTC (OR = 1.058, 95% CI: 1.009, 1.110) in a non-linear dose–response relationship, but there was no association between perchlorate and NG or PTMC. Iodine was not associated with the risk of thyroid tumors and NG and did not correlate with the thyroid function indicators. Furthermore, perchlorate showed a positive correlation with thyroid stimulating hormone (TSH) at iodine adequate levels ( P   〈  0.05), and a negative correlation with free triiodothyronine (FT3) and a positive correlation with thyroglobulin antibody (TgAb) at iodine more than adequate or excess levels ( P   〈  0.05). Conclusions Perchlorate can increase the risk of PTC in a non-linear dose–response relationship and disturb the thyroid hormone homeostasis and thyroid autoantibody levels.
    Type of Medium: Online Resource
    ISSN: 1476-069X
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2092232-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    In: Pharmaceutical Biology, Informa UK Limited, Vol. 60, No. 1 ( 2022-12-31), p. 2300-2307
    Type of Medium: Online Resource
    ISSN: 1388-0209 , 1744-5116
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2022
    detail.hit.zdb_id: 1483151-X
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    Online Resource
    Online Resource
    Frontiers Media SA ; 2023
    In:  Frontiers in Plant Science Vol. 13 ( 2023-1-13)
    In: Frontiers in Plant Science, Frontiers Media SA, Vol. 13 ( 2023-1-13)
    Abstract: Trigenomic Brassica allohexaploids (AABBCC, 2n = 6x = 54) have great potential in oilseed breeding and genetic diversity. However, Brassica allohexaploids do not exist naturally, and the underlying mechanism regulating pollen fertility in artificially synthesized Brassica allohexaploids is still unclear. In this study, synthetic Brassica allohexaploids were produced by crossing allotetraploid B. carinata (BBCC, 2n = 4x = 34) and diploid B. rapa (AA, 2n = 2x = 20), followed by chromosome doubling. The results showed that the pollen fertility was significantly reduced and the pollen structures were mostly distorted, but the nursing anther tapetum developed normally in the synthetic Brassica allohexaploids. Furthermore, the data showed that the meiotic events occurred irregularly with uneven chromosome segregation and microspore development appeared mostly abnormal. Transcription analysis showed that the upregulation of genes related to the negative regulation of flower development and the downregulation of genes related to chromosome segregation might play an essential role in reduction of pollen fertility in the Brassica allohexaploids. In conclusion, this study elucidated the related mechanisms affecting pollen fertility during male gametophytic development at the cytological and transcriptomic levels in the newly synthesized Brassica allohexaploids.
    Type of Medium: Online Resource
    ISSN: 1664-462X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
    detail.hit.zdb_id: 2687947-5
    detail.hit.zdb_id: 2613694-6
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    Online Resource
    Online Resource
    Elsevier BV ; 2020
    In:  Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology Vol. 130, No. 1 ( 2020-07), p. 25-31
    In: Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, Elsevier BV, Vol. 130, No. 1 ( 2020-07), p. 25-31
    Type of Medium: Online Resource
    ISSN: 2212-4403
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
    detail.hit.zdb_id: 2001803-4
    detail.hit.zdb_id: 2650551-4
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...